Ed Yong in The Atlantic:
There’s a joke about immunology, which Jessica Metcalf of Princeton recently told me. An immunologist and a cardiologist are kidnapped. The kidnappers threaten to shoot one of them, but promise to spare whoever has made the greater contribution to humanity. The cardiologist says, “Well, I’ve identified drugs that have saved the lives of millions of people.” Impressed, the kidnappers turn to the immunologist. “What have you done?” they ask. The immunologist says, “The thing is, the immune system is very complicated …” And the cardiologist says, “Just shoot me now.”
The thing is, the immune system is very complicated. Arguably the most complex part of the human body outside the brain, it’s an absurdly intricate network of cells and molecules that protect us from dangerous viruses and other microbes. These components summon, amplify, rile, calm, and transform one another: Picture a thousand Rube Goldberg machines, some of which are aggressively smashing things to pieces. Now imagine that their components are labeled with what looks like a string of highly secure passwords: CD8+, IL-1β, IFN-γ. Immunology confuses even biology professors who aren’t immunologists—hence Metcalf’s joke.